Measuring electrical signals in the body has relied on bulky equipment, …

Modern methods of measuring the body's activty, such as electroencephalography (EEG), electrocardiography (ECG), and electromyography (EMG), use electrical signals to measure changes in brain, heart, and muscle activity, respectively. Unfortunately, they rely on bulky and uncomfortable electrodes that are mounted using adhesive tape and conductive gel—or even needles. Because of this, these types of measurements are limited to research and hospital settings and typically used over short periods of time because the contacts can irritate skin.

These limitations may be at an end, however. New research published in Science describes technology that allows electrical measurements (and other measurements, such as temperature and strain) using ultra-thin polymers with embedded circuit elements. These devices connect to skin without adhesives, are practically unnoticeable, and can even be attached via temporary tattoo.

All of the necessary components of the devices, including electrodes, electronic components, sensors, radio frequency communication components, and power supplies, are set within an extremely thin (about 30 μm) elastic polyester sheet. The sheet has a low elastic modulus (that is, it's flexible) and no noticeable mass (about 0.09 g), so you have a lightweight, stretchable membrane.

Circuit elements (such as transistors, diodes, resistors) and sensors are constructed with typical materials like silicon and gallium arsenide, but are linked using nanoribbon and micro/nanomembrane elements to allow extremely small but flexible designs.

The authors refer to their approach as an "epidermal electronic system" (EES), which is basically a fancy way of saying that the device matches the physical properties of the skin (such as stiffness), and its thickness matches that of skin features (wrinkles, creases, etc.). In fact, it adheres to skin only using van der Waals forces—the forces of attraction between atoms and molecules—so no adhesive material is required. Between the flexibility and the lack of adhesive, you wouldn’t really notice one of these attached.

One of the coolest aspects of this technology is the application method: temporary (transfer) tattoo. Yes, the ones you used as a kid, where you hold the transfer sheet with the design onto your skin then dampen it to dissolve the sheet. Here, they used water-soluble polyvinyl alcohol (PVA) sheets in the same manner.

For a power supply, initial designs used silicon photovoltaic cells to generate electricity, but these are limited to microwatts due to the small area. Researchers also explored wireless inductive power, where an external transmission coil matches the resonance frequency of a small inductive coil in the device (it's the same sort of tech that's used in wireless device chargers). This opens up the door for applications that need more power than solar can provide, or for devices that work in low-light conditions (under clothing, for example). The authors also suggest future electrical storage using capacitors or batteries.

As demonstrations, the authors used their devices to measure heartbeats on the chest (ECG), muscle contractions in the leg (EMG), and alpha waves through the forehead (EEG). The results were all high quality, comparing well against traditional electrode/conductive gel measurements in the same locations. In addition, the devices continuously captured data for six hours, and the devices could be worn for a full 24 hours without any degradation or skin irritation.

One interesting demonstration that also suggests future applications was the measuring of throat muscle activity during speech. Different words showed distinctive signals, and a computer analysis enabled the authors to recognize the vocabulary being used.

The team even hooked one of these sensors up to a simple computer game (Sokoban) and used throat activity as the controller. Identifying each word took about three seconds using a MATLAB program, but it had a higher than 90 percent accuracy. (That's probably just good enough to leave gamers seriously frustrated.) While the potential videogame applications are endless, you can also think of other areas, such as silent communications or better voice recognition software.

The authors suggest there are a huge number of applications for this technology, including remote medical monitoring, biological/chemical sensing, human-machine interface, and covert communications. There are a couple areas where further development is needed, however: RF communication frequencies change when the circuits are stretched, and dead skin and sweat have to be dealt with during long-term use. These aren’t insurmountable complications, though, so we'll be interested in following this as further work is done (the unclassified work, at least).

I thought this was going to be the tattoo sensors that I read about on the MIT site but it's not. This is cool too but the ones on the MIT site where more elaborate and actually went into the skin to measure blood gasses and such. Looks like both of these researchers are onto something either way.

This would have insanely awesome applications for the disabled. Video games would also benefit with some insanely cool combinations with kinect and other motion systems, all we need now is a virtual reality chamber and we're all set.

Astonishingly cool, but that means eventually a friendly pat on the back could have Big Brother applications!

I was kinda worry about that myself 'til it says it only last for 6 hours. What a relief, man, I tell you. Now if anyone pat on my shoulder I just locked myself up in the closet and 6 hours later it'll be all good as new.

Maybe they should use metal-air batteries. They have high energy densities, would start operating on application, require no external devices, and you can match the Wh to the desired duration reducing privacy concerns.

Fun question to ask the God-botherers: why is Revelation strictly metaphorical until chapter 14, and then far more literal thereafter? Eg. the "mark of the beast" in 13 is barcodes, but the "4 plagues" in 15 are literal.

Didnt I read about this technology somewhere before ah yes perhaps you have also read the same book. None shall be able to buy or sell anything without the mark of the beast upon their skin. Seems somebody is doing the devils work for him.

This is awesome -- to me it just looks like semiconductor dies without packaging. Pretty brilliant stuff. Just hope it one day makes it past the "proof of concept" stage (unlike 95% of all other scientific innovations featured in tech articles like this).

I know a nice Irish pub that's here in the states that produces one of the best burgers in the country - they have Guinness on draft as well!

jonnybond wrote:

Didnt I read about this technology somewhere before ah yes perhaps you have also read the same book. None shall be able to buy or sell anything without the mark of the beast upon their skin. Seems somebody is doing the devils work for him.

So, having "The Number of the Beast Tattooed upon your forehead" is the same as an epidermal temporary tattoo that conveys biometric information? Seriously? And Christians wonder why the rest of the world laughs at them. Let's suspend reality for just a moment and contemplate the Bible as something other than fiction - Revelations is a DREAM. Dreams are open to interpretation (as the rest of the Bible is - honestly, the world is only a few thousand years old and it was made in six days? Jesus was without food and water for 30 days and 30 nights? Riiighhhtt...your straight jacket is over there, sir...buckles to the back please) and therefore the "mark of the beast" as well as his "number" are parts of the dream and therefore open (wide open, I might add) to interpretation as to what they are and mean.

Assuming a LITERAL TATTOO would mean you should also assume a LITERAL '666'

This is awesome -- to me it just looks like semiconductor dies without packaging. Pretty brilliant stuff. Just hope it one day makes it past the "proof of concept" stage (unlike 95% of all other scientific innovations featured in tech articles like this).

Hospitals alone would be an obvious multibillion$ market, so I'm pretty sure this will get a lot of attention from some very deep pockets. Of course it will probably take years - if not decades, for this to see mass adoption in healthcare, but I'm pretty sure someone will try.

Speaking as a nurse, the awesomeness of this is enormous. It would make a huge difference for remote ECG monitoring (which requires equipment like this today); for instantly available ECGs on demand (in the real world it will usually take at least 10 minutes and sometimes hours before an ECG is ready); for neurological and sleep monitoring etc.

I don't really see the big privacy issues of this. To get usefull data, you need relatively precise placement and usually several electrodes... there is no way these can be usefully placed on a conscious person without getting noticed. And it isn't as if transmissions go for several kilometers.Even if you drugged someone and attached it while they were sleeping, I don't really see covert ECG monitoring as much of a privacy invasion risk anyway. Maybe insurance companies would like it, but there are easier ways to get medical records than making them yourself (like from a hospital).If all you're looking for is uniquely identifying someone remotely, then it is an awfully big amount of work to use these... slap an RFID chip on someone and call it a day.

Speaking as a nurse, the awesomeness of this is enormous. It would make a huge difference for remote ECG monitoring (which requires equipment like this today); for instantly available ECGs on demand (in the real world it will usually take at least 10 minutes and sometimes hours before an ECG is ready); for neurological and sleep monitoring etc.

As someone who just finished up a 10 day monitoring period, i'm happy to report they can now get away with only 3 electrodes. Unfortunately, i'm both allergic to the electrode adhesive and have a fairly hairy chest, so developing these into a product would definitely be a big, big positive from my perspective.

Kind of scary. Just imagine the info one can steal from an unknowing individual with one of these.

A pick pocket can steal your wallet in a few seconds or less and no loud cries of "conspiracy theory" or "tin foil hats" are going to dismiss that fact. That said they certainly could easily plant one of these on the back of someone’s neck and the person not know it for a while. Just like most innovations they can be used for good or for bad.

The Hollerith punch card was used to harm men & women in World War era Germany but later used to help man (here in the US) and so innovations can also be both good and bad at the same time.

It’s what we in society let big corporate and government do with these innovations that ultimately determine if they will benefit or harm man.

Kind of scary. Just imagine the info one can steal from an unknowing individual with one of these.

These things measure electrical currents in your body, they don't read your mind.I'm not saying your cardiac arrythmia or whatever is anyone elses bussiness (unless you so choose), but what is the scary part?

Kyle Niemeyer / Kyle is a science writer for Ars Technica. He is a postdoctoral scholar at Oregon State University and has a Ph.D. in mechanical engineering from Case Western Reserve University. Kyle's research focuses on combustion modeling.